Track-type work vehicles, such as bulldozers, have a track type carrier. The track type carrier has a track apparatus, a sprocket wheel, an idler tumbler, a roller device, and the like. The track apparatus is generally structured by coupling a plurality of track links endlessly with pins and bushings and attaching a track shoe plate to the plurality of track links. The track apparatus is wound around the sprocket wheel, the idler tumbler and the roller device, and is configured to be capable of rotationally driving by engaging the teeth of the sprocket wheel with the above-mentioned bushings to rotate the sprocket wheel.
The roller device has a shaft, a bushing, a roller shell, and the like. The shaft is fixed to a work vehicle. The roller shell is rotatably supported by the shaft with the bushing interposed therebetween. The roller shell is worn by rolling over rail surfaces of the track links during traveling. As the wear of the roller shell progresses, the roller shell needs to be replaced. When replacing the roller shell, there is a technique for replacing the whole roller device. However, this technique increases the cost. Therefore, a technique for replacing the roller shell alone rather than the whole roller device has been proposed. This technique for replacing the roller shell alone rather than the whole roller device is disclosed in, for example, Japanese Patent Laying-Open No. 50-90026 (PTD 1).